The Department of Justice will investigate the practices of police in Ferguson, Missouri, looking for a pattern of discrimination and use of unlawful force, The New York Times reported.

The FBI is already probing the Aug. 9. shooting of an 18-year-old African American, Michael Brown, by Officer Darren Wilson, 28, who stopped him initially for blocking traffic. Wilson has not been charged with any misconduct, the Times reported.

The wider civil rights inquiry was first raised by Attorney General Eric Holder in the immediate aftermath of the incident. It will seek to substantiate complaints that the police continually violated the civil rights of residents.

The investigation could be expanded to include other St. Louis County departments, according to the Times.

Ferguson is a predominantly black city of 20,000 with an overwhelmingly white police force. Black leaders have complained that suburban St. Louis police routinely harass blacks.

In an incident last year near the South County Center shopping mall, two white officers from the St. Louis County Police Department invested 30 days in arresting 145 African Americans for outstanding warrants, the Times reported.

"We determined that the stops were not legitimate stops," said Adolphus Pruitt, a local NAACP leader. "They stopped them because they were black. The question is, how many blacks did they have to go through to find 145 with warrants?"

Holder's Justice Department has opened a record 20 investigations into police departments around the country and reached agreements with 13 for ongoing monitoring of their activities, the Times reported.

The Ferguson shooting led to days of rioting and charges that police overreacted by fielding military-style units to quell the troubles.

To charge Wilson with a civil rights violation, Justice Department investigators would need to establish that he intended to violate Brown's civil rights – that he knew he shouldn't but shot him anyway, according to the Times.

"We have no intentional policies or procedures which discriminated or violated civil rights. But if we have anything there which may unintentionally do that, we need to know about it," the Times reported.